There are conventionally known techniques of imparting lubricity to medical device surfaces by coating (e.g., Patent Publication 1). Patent Publication 2 proposes use of a copolymer of 2-methacryloyloxyethyl-2-trimethylammonioethyl phosphate (abbreviated as MPC hereinbelow) and allylamine (abbreviated as AAM hereinbelow) on medical device surfaces for improved biocompatibility.
However, AAM is highly toxic and inconvenient in handling, so that it is not preferred to increase the compositional ratio of AAM in the copolymer.
Patent Publication 3 proposes reacting MPC copolymer having primary amino groups, which is obtained by copolymerization of MPC and 2-aminoethylmethacrylate (abbreviated as AEMA hereinbelow), with reactive surfaces of medical devices. According to this method, the copolymer having highly reactive amino groups is chemically bonded to medical device surfaces, so that an increased amount of amino groups are introduced, resulting in highly durable surfaces.
However, cationic property of the functional groups remaining unreacted may cause protein adsorption, activation of immune cells, or adsorption to cells, which may deteriorate the biocompatibility.    Patent Publication 1: JP-H05-300940-A    Patent Publication 2: WO 2001/05855    Patent Publication 3: US-6090901